Renewable energy sources, such as biofuels, provide a substitute for fossil fuels and a means of reducing dependence on petroleum oil. In light of its low cost and wide availability, solid biomass is often used as a feedstock to produce bio-oil which, in turn, is used to produce biofuel.
Many different conversion processes have been developed for converting solid biomass to bio-oil in a biomass conversion unit. Existing biomass conversion processes include, for example, thermolysis, such as slow pyrolysis and fast pyrolysis, and catalytic thermolysis. Thermolysis is characterized by the thermal decomposition of materials in an oxygen-poor or oxygen-free atmosphere (i.e., significantly less oxygen than required for complete combustion). The liquid product resulting from thermolysis of biomass includes organic materials. In some instances, the liquid product may be separated into an aqueous phase and an organic phase. The organic phase is commonly referred to as bio-oil. Bio-oil may be processed into transportation fuels as well as into hydrocarbon chemicals and/or specialty chemicals.
In addition to liquid reaction products, pyrolysis produces gaseous reaction products and solid reaction products. Gaseous reaction products include carbon dioxide, carbon monoxide, and relatively minor amounts of hydrogen, methane, and ethylene. Solid reaction products include carbonaceous deposits, such as coke and char. Such solids reduce the yield of bio-oil and are largely removed after the converted biomass exits the biomass conversion unit.
In order to maximize the liquid yield, while minimizing the solid and non-condensable gaseous reaction products, thermolysis is conducted at a relatively fast heating rate of the biomass feedstock. For example, the biomass may be rapidly heated between 150 and 600° C. and the reaction time kept short, i.e. on the order of milli-seconds to seconds. Such fast thermolysis results in high yields of primary, non-equilibrium liquids and gases (including valuable chemicals, chemical intermediates, petrochemicals and fuels).
There is a significant incentive to increase the yield of organic liquid products obtained by pyrolysis. To do so, it is necessary to enhance the yield of volatile condensable oily products (e.g., organic liquids) and reduce the levels of coke, char, gases (such as carbon monoxide and carbon dioxide).
It should be understood that the above-described discussion is provided for illustrative purposes only and is not intended to limit the scope or subject matter of the appended claims or those of any related patent application or patent. Thus, none of the appended claims or claims of any related application or patent should be limited by the above discussion or construed to address, include or exclude each or any of the above-cited features or disadvantages.